What Can You Do with CO2?

As every reader of this blog knows, atmospheric levels of carbon dioxide, CO2, the chemical product of combustion, are rising. So are the levels of dissolved CO2 in the ocean. Scientists believe that a number of recent phenomena (rising temperatures on a global scale, increased acidification of oceans, shifts in precipitation patterns, etc.) are associated with these rising levels and that the downsides of these changes may be very costly. So what to do? Produce less CO2 in the first place? Or, maybe find a way to “hide” or “remove” CO2 once it is formed?

Two journals, Science and the Journal of Physical Chemistry Letters, have recently published articles on the problems associated with hiding/removing CO2 (sometimes called CO2 capture and CO2 sequestration). Here’s a quick look at the articles and some links (warning: some of these links require a subscription):

Science magazine (25 September 2009) released a special issue (25 September 2009) on Carbon Capture and Sequestration (CCS). The introduction, Clearing the Air, describes the articles this way:

“… In the Review, Haszeldine (p. 1647, “Carbon Capture & Storage: How Green Can Black Be?”) surveys efforts around the world to capture and store CO2 emitted by power plants, discussing both the technological challenges of carbon capture, transport, and storage and the political hurdles that remain to be overcome. Four Perspectives then highlight specific approaches to both CO2 capture and CO2 sequestration. Rochelle (p. 1652, “Amine Scrubbing for CO2 Capture”) discusses how CO2 can be removed from the flue gas of power plants by the well-established technique of amine scrubbing, an especially important activity given the current reliance on coal. Keith (p. 1654, “Why Capture CO2 from the Atmosphere?”) presents ideas about removing CO2 directly from ambient air, one of the few approaches that offer the possibility of reducing the concentration of CO2 in the atmosphere on a time scale of decades. Orr (p. 1656, “Onshore Geologic Storage of CO2”) discusses the current strategy of choice for sequestering captured CO2 permanently: the storage of CO2 in onshore geologic formations. Finally, Schrag (p. 1658, “Storage of Carbon Dioxide in Offshore Sediments”) argues for another promising but rarely discussed way to sequester CO2: through storage in offshore sediments.

The Journal of Physical Chemistry Letters published several articles in 2010 about chemistry of CCS, including a Guest Commentary, “What To Do with CO2?” (p. 3478) by Prof. E.J. Maginn. Maginn begins by explaining the enormous scale of the problem:

“All human activity generates about 37 billion tons (37 Gt) of CO2 emissions each year, with about 30 Gt of this coming from energy-related emissions.[ref 2] Total emissions were less than 25 Gt twenty years ago, and under business as usual scenarios, emissions are projected to rise to over 50 Gt twenty years from now. A gigaton is an almost incomprehensibly large number. As a point of reference, the world annually consumes around 0.2 Gt of sulfuric acid,[ref 3] while the U.S. consumes less than 0.5 Gt of gasoline.[ref 2] Think of the enormous infrastructure built up over the last 100 years to produce commodity chemicals like sulfuric acid or the refining and distribution systems in place to produce gasoline. Then, imagine having to build systems that can handle quantities of CO2 orders of magnitude larger than these. This is no small problem.”

Although you can’t go into Fred Meyer and purchase a photocatalytic CCS system for your home’s furnace today, it seems possible that a committed application of intelligence and effort might lead to practical CCS before the greenhouse gets too hot.